Thermosyphon and Bath Cooling Techniques for SHe/LHe Heat Exchange in Cryogenic Aluminum Plate-Fin Heat Exchanger

Abstract

Aluminum Plate-Fin Heat Exchangers (PFHE) found many applications in the cryogenic process industries, petrochemical plants and refrigeration units ranging from Liquefied Natural Gas (LNG), Air Separation Units (ASU) to Helium Cryo- genics. Its compact design offers high heat transfer area to volume ratio and thus great thermal performance. Aluminium PFHE's unique capabilities to provide min- imum temperature approach between the streams and accommodate many streams in the same unit gives flexibility in process flow design and small fluid inventory with consequent improvement in control safety and product quality. In the present study the various cooling modes, i.e., bath cooling and natural convection through thermosyphon effect will be studied in detailed for Supercritical Helium (SHe), a hot stream, to Liquid Helium (LHe), a cold stream, heat exchange of 10 kW class dy- namic heat load at 4 K temperature level. Thermo-hydraulic design of Aluminium PFHE under the various geometrical parameters like fin type, pitch, number of passes etc. with temperature dependent fluid properties have been carried out. A comparative analytical study have been made for thermosyphon cooling with bath type cooling and the results were compared.